Allosteric inhibitor combines at allosteric site and not the active site. Drugs inhibit the attachment of substrate on active site of enzymes in two different ways;
(ii) Some drugs do not bind to the enzyme's active site. These bind to a different site of enzyme which is called allosteric site. This binding of inhibitor at allosteric site changes the shape of the active site in such a way that substrate cannot recognize it. This is also called non-competitive inhibitor.